Temperatures stable saw sensor with third-order elastic constants
US7202589B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 16, 2002 |
| Grant date | Apr 10, 2007 |
| Priority date | — |
| Expiry date | Aug 30, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L3/106
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A surface acoustic wave (SAW) sensor includes a transducer (240 provided on a substrate (23), wherein the transducer (24) is oriented on the substrate (23) so that the direction of acoustic wave propagation is such that the variation of sensor output with temperature, associated with the variation of the substrate third-elastic constants with temperature, substantially equal but opposite to the sum total of the variation of sensor output with temperature associated with the substrate linear temperature coefficient of expansion and with the variations with temperature of the substrate non-zero third order elastic constants, the substrate first-order elastic constants and the substrate density. The effect of temperature variation on sensor output is thereby minimized. This is achieved with a 35-degree arrangement or with reflective gratings inclined at an angle of 3.1 degrees to normal. Additionally, a robust package with a dish is given. Particular applications include the measurement of torque.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.